JP2003273874A - Discrimination method of device supporting mcap on the same network, and multicast communication method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discrimination method of devices, supporting MCAP (Multicast Channel Allocation Protocol) over the same network and multicast communication method using it. <P>SOLUTION: A confirmation method as to whether MCAP is supported including (a) a process, in which a MCAP supporting device 402 broadcasts a MCAP broadcast message to all devices 404, 406 over the same network, (b) a process in which the MCAP support device that has broadcasted the MCAP broadcast message, broadcasts an IGMP (Internet Group Management Protocol) inquiry message to all devices over the same network, (c) a process in which the MCAP supporting device that has broadcasted the MCAP broadcast message, discriminates whether each device supports the MCAP by a channel number on which the IGMP reporting message is transmitted from the all devices on the same network. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for identifying whether or not a device that supports MCAP and a device that does not support MCAP exist on the same network at the same time, and a multicast method using the method. Regarding communication method.

[0002]

2. Description of the Related Art A conventional multicast communication method performs multicast communication using a broadcast channel regardless of whether a device belonging to the same network, for example, an IEEE 1394 network supports MCAP. In this case, even if all devices support MCAP, the MCAP function itself is uselessly disabled by using the broadcast method, and as a result, the selective transmission function, which is the core function of multicast communication, cannot be used.

[0003]

SUMMARY OF THE INVENTION The present invention has been devised to solve the above-mentioned problems, and an object thereof is to provide a method of identifying a device that supports MCAP on the same network.

Another object of the present invention is to provide a multicast communication method using the above identification method.

[0005]

A method for identifying whether or not to support MCAP according to the present invention which achieves the above object,
(A) A process in which the MCAP support device broadcasts the MCAP broadcast message to all devices on the same network; and (b) The MC that broadcasts the MCAP broadcast message.
A process in which the AP support device broadcasts an IGMP inquiry message to all devices on the same network, and (c) the MCAP support device that broadcasts the MCAP broadcast message transmits an IGMP report message from all devices on the same network. Depending on the channel number
And a step of identifying whether or not to support.

[0006] A multicast communication method according to the present invention which achieves the above-mentioned other object, comprises: (a) a process in which an MCAP support device broadcasts an MCAP broadcast message to all devices on the same network; and (b) the MCAP broadcast. A process in which the MCAP supporting device that broadcasts the message broadcasts the IGMP inquiry message to all devices on the same network, and (c) the MCAP that broadcasts the MCAP broadcast message.
A process in which the supporting device identifies whether or not each device supports MCAP based on a channel number through which an IGMP report message from any device on the same network is transmitted, and (e) any device that broadcasts the MCAP broadcast message. If the IGMP report message from the is transmitted through the multicast channel, the multicast channel is used for transmission and reception, and if at least one is transmitted through the broadcast channel, the multicast channel is used for transmission and reception. It is characterized by including the process performed by

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure and operation of the present invention will be described in detail below with reference to the accompanying drawings.

[0008] The transmission method of the Internet can be classified into unicast, broadcast and multicast from the viewpoint of sender and receiver participating in the transmission.

FIG. 1 is a diagram schematically showing a unicast system, a broadcast system and a multicast system.

The unicast transmission method is a method in which one sender transmits data to another receiver, and general Internet applications use this unicast method. On the other hand, the broadcast transmission method is a method in which one sender transmits data to all receivers on the same subnetwork.

On the other hand, the multicast transmission method is a method in which one or more senders transmit data to specific one or more receivers, and is used as an application such as an Internet image conference.

When the same data is to be transmitted to multiple receivers for group communication, if the unicast transmission method is used, the data packet to be transmitted must be transmitted to a large number of receivers several times each. The network efficiency decreases due to the duplicate transmission of the same packet. In addition, such a problem becomes more serious when the number of recipients increases.

On the other hand, if the multicast transmission is supported, the sender can transmit the message at one time, and the waste of network resources due to the duplicate transmission of data can be minimized.

The difference between multicast transmission and general unicast transmission lies in the transmission packet. Generally, Internet application programs on TCP / IP are
The sender of the data displays the Internet address of the receiver who receives the data in the header of the transmission packet and transmits the packet. However, for multicast transmission, the group address to which the receiver belongs is displayed in the header instead of the address of the receiver, and the packet is transmitted.

The group address for multicast transmission is a class D IP address (224.0.0.0-23).
9.255.255.255), which is different from Class A, B, and C IP addresses that indicate individual Internet hosts in the world, and is not an address that represents an actual host, but a multicast packet that has a group address. The receiver determines whether or not the packet is acceptable by judging whether or not it belongs to the group of packets.

IP multicast addressing is performed by R
FC1112 (Host Extensions for
It is an Internet standard defined by IP Multicasting and is supported by many workstation companies (SUN, SGI, DEC, HP, etc.),
It is officially defined as an IP class D address.

The class D address range is 224.0.0.1.
To 239.255.255.254, this address is not uniquely assigned to a particular host and is actively assigned to one multicast group, which is different from the previous address assignment scheme.

A workstation that can recognize class D, that is, a workstation that supports IP multicast, exchanges information by using two addresses of a multicast group that it belongs / desirs to belong to in addition to the supported unique address. A protocol called IGMP defines a method in which a host must be exchanged when forming a new group or belonging to this group. A typical means for displaying a multicast group configured in this way is s
d (session display), it can be used to confirm what multicast group is currently operating and what these components are.

On the other hand, the IEEE 1394, which has begun to receive attention as an interface technology for the next-generation home network, was originally developed as a hard disk interface by Apple Inc. in 1986. Later, IBM and Sony joined forces to promote standardization work, and in 1994, IEEE
1394 Trade As to spread 1394
sociation was established.

In 1995, officially IEEE Std 1
A standard was approved under the name 394-1995, but this standard proposal has three high-speed transmission rates of 100 Mbp.
s, 200 Mbps, and 400 Mbps are standardized. IE that added this function in 2000 and complemented it
The EE Std 1394a-2000 standard has been standardized.

FIG. 2 is a schematic diagram showing the relationship between layers in IEEE 1394.

IEEE 1394-1995 is a hardware and software standard consisting of three layers, a physical layer, a link layer, and a transaction layer. FIG. 2 diagrammatically expresses the relationship between these three layers and their respective functions. Generally, the IEEE 1394 host adapter plays a role of a physical layer and a link layer, and a host takes charge of a transaction layer and a bus management function. The physical layer mainly performs an arbitration function to acquire the right to use the serial bus, and the cycle control of the bus is in charge of the data link layer. The transaction layer is a basic function of network devices-reading,
Writing is performed, and the bus control function is in charge of resource management required for simultaneous transmission.

The IEEE 1394 interface is
The serial interface is basically composed of 6 copper wires, and each of these 6 wires consists of 2 pairs of signal lines and 1 pair of power supply lines. Two pairs of signal lines are used in half duplex,
One pair is used to transmit a data signal, and the other pair is used to transmit a timing signal for sampling synchronization of data. The reason for using the pair of signal lines as timing information is that the data is Manchester-coded (manchester codi) because the transmission speed is high.
This is to prevent the transmission rate from doubling when the timing information such as ng) is included.

A device that supports IEEE 1394 is called a node. The most common physical connection method for connecting nodes is a tree structure and a usage method is a bus structure. That is, only one node can transmit data at any given time and all connected nodes can receive it.

The standard for supporting IP multicast on the IEEE 1394 network is IETF (Int).
ernet Engineering Task For
ce, IAB developing Internet standards
(Internet Architecture Boa
rd) draft-ietf-i of the research committee under its umbrella
p1394-ipv6 and draft-ietf-ip1
394-mcap, and in the case of IPv4, RFC2734 (IPv4 over IEEE139
It is defined in 4). In these standards, IP multicast packets are defined to be supported by using an asynchronous stream transmission mode and an isochronous stream transmission mode. At this time, the mode to be used is selected according to the service request characteristics of the IP packet. That is, the asynchronous stream method is best-effort (Best-Eff).
ort) service and isochronous stream method are QoS (Q
It is used for packets that require "alertity of Service".

In these two transmission methods, the channel number is used instead of the node number for transmission, but the processes such as channel number allocation and return, and bandwidth allocation are performed by CAM (Channel Allocation Ma).
), using the MCAP protocol. The CAM allocates a multicast channel and bandwidth at the request of a multicast source or a group member. The request and response packets used at this time use the MCAP protocol.

The MCAP defines two methods for channel allocation. First, all nodes that perform IP functions (devices that support IEEE 1394)
How to use a shared broadcast channel. Second, a method of allocating and using channels other than broadcast channels.

The first method can perform multicast communication without using another protocol, but since unnecessary packets are received by the device, the calculation load of the device is increased.

In the case of the second method, one device belonging to a specific multicast group is assigned a channel for the corresponding multicast group address, and all devices on the network are connected to the corresponding multicast address and the assigned channel through an MCAP broadcast message. Inform the sex. Every node on the network that receives the MCAP broadcast message must send / receive the corresponding multicast packet through the designated channel.

If every device on the IEEE 1394 network uses the broadcast channel as in the first case, no problem occurs in the multicast communication. However, it is necessary to accept the phenomenon that unnecessary packets increase the calculation load of devices that do not belong to the corresponding multicast group by broadcasting.

All devices on the network are the second
The problem does not occur even in the case of the MCAP support device that interprets the MCAP message and adjusts the channel according to the MCAP message. In this case, reception of unnecessary packets can be minimized.

As described above, when all devices do not implement the MCAP function, or when all the devices are MCAP.
No problem occurs in multicast communication when supporting.

However, at present, all nodes on the IEEE 1394 network cannot support MCAP, and multicast communication is performed by an inconvenient broadcast method because MCAP supporting devices and non-supporting devices are mixed. It's a reality.

FIG. 3 schematically shows a conventional multicast communication system on the IEEE 1394 network.

As a conventional multicast communication method on the IEEE 1394 network, a method of transmitting one multicast message to all devices through a broadcast channel (channel l31) as shown in FIG. 3A is used. In such cases, M
It can be used by configuring any device, regardless of the CAP supporting devices 302, 306 and the non-supporting device 304, to broadcast the multicast message.

However, for example, the MCAP support device 306
3 instead of using the broadcast channel
As shown in (b), another channel, for example, channel 7
A problem occurs when multicast is assigned by assigning.

That is, the MCAP support device 306 determines that the multicast address (for example, 239.255.25)
5.250), assigning channel 7 to MCA
If the P message is transmitted and the MCAP supporting device 302 that recognizes the P message transmits a multicast message having an address of 239.255.255.250 through the channel 7, the MCAP non-supporting device 304 cannot receive this multicast message. .

As described above, when the MCAP non-supporting device and the MCAP supporting device, which are fixed so as to perform the multicast only on the broadcast channel without supporting the MCAP, coexist on one network, the communication between the both devices is performed. There is difficulty.

That is, even if the MCAP supporting device allocates a channel other than the broadcast channel to the specific multicast address and informs this to all devices in the network through the MCAP broadcast message, the MCAP non-supporting device broadcasts the multicast packet on the broadcast channel. Since it is fixed to send and receive, it becomes impossible to receive packets of differently assigned channels.

Such a problem may cause a serious problem in a home network environment. In the future home network environment, PCs, laptops, palmtops, TV set-top boxes (STBs), video game consoles, printers, modems, scanners, mobile phones, etc. Home appliances such as Internet phones, digital answering machines, pagers, refrigerators, and toasters are connected all at once.

The device connected to the host in the home network is a network PnP (Plug and P).
lay) function.

For example, UPnP (Universal
Plug and Play) was developed by Microsoft Corporation, and is a type of network PnP like Jini (registered trademark) developed by Sun Microsystems.

In the case of UPnP, it is a relay that connects devices interactively and uses a new network protocol. That is, it is a method of distributing data requesting the HTTP protocol to the right place regardless of the type of computer connected to the web server, such as HTTP which is a hypertext transmission protocol. Actually, from the window 2000, IPP (Internet Print)
ing Protocol) is supported,
It was implemented so that the user's document could be output remotely using a printer connected on the network. Of course, IP
The P protocol does not depend on the user's operating system, printer manufacturing, or model.

On the other hand, in Jini (registered trademark), Java (registered trademark) takes charge of the role of a protocol such as IPP of MS. Most existing PCs are J
If there is only a web browser that supports ava (registered trademark), the Java (registered trademark) applet is downloaded from the server and operates. Therefore, by supporting the Java (registered trademark) applet that recognizes the device by focusing on this point, the applet is downloaded at any time and immediately disappeared on the machine when it is not needed. The core is RMI
(Remote Method Invocation)
Is. Particularly, from a user's standpoint, there is an advantage that the process of downloading or deleting the Java (registered trademark) applet cannot be visually identified.

In such a home network having variability / extendability by the network PnP, the IE
It is necessary to efficiently manage the traffic between the devices existing on the EE1394 network, and especially to prevent unnecessary packets from being transmitted for multicast communication.

In order to solve this, the present invention determines whether or not there is a device that does not support MCAP on the same network.
MCAP by using MP inquiry / report message
The MCAP supporting device uses the broadcast channel only when there is a device that does not support MCAP, and when all devices support MCAP, multicast transmission is performed by the MCAP protocol.

By doing so, it is possible to prevent all the devices belonging to the multicast group on the IEEE 1394 network from using the broadcast channel unnecessarily to give a computational load to the devices even when supporting the MCAP. Even if there is an MCAP non-supporting device in the corresponding multicast group, it is possible to obtain the effect of performing multicast communication.

FIG. 4 is a flowchart showing a method of identifying whether to support MCAP according to the present invention.
4 schematically shows the process shown in FIG.

Referring to FIGS. 4 and 5, M according to the present invention
A method of identifying whether to support CAP will be described in detail.

First, as shown in FIG. 4, the MCAP supporting device allocates an arbitrary channel that is not a broadcast channel to a multicast address, and then the same IEEE 13 is used through this multicast channel.
Broadcast an MCAP broadcast message to all devices on the 94 network (S
402).

For example, as shown in FIG. 5, after the MCAP supporting device 402 belonging to the multicast group 239.2525.255.250 allocates channel 7 to the multicast address, it is sent through the broadcast channel (channel 31). Same IEEE139
4 Broadcast an MCAP broadcast message to every device on the network.

Next, the MCAP support device 402 that has broadcast the MCAP broadcast message
The IGMP inquiry message is broadcast to all devices 404 and 406 on the same IEEE 1394 network through the broadcast channel (channel 31) (S404).

The IGMP protocol is responsible for the joining / leaving process for the multicast group. IGMP is
Used by multicast routers to recognize the existence of host group members on their subnet.

The IGMP protocol basically uses inquiry and report messages. The inquiry message is IGMP
It is a message that the protocol asks if there are any hosts joining the group. It is now periodically transmitted to the subnet to identify the members of the group. The report message is a reply to the inquiry message,
Only sent by hosts that are willing to join the group.

If the IGMP sends an inquiry message to the corresponding subnet, only the host desiring to join the corresponding multicast group can join the group by sending a report message. The withdrawal of a group must be done without a response to the inquiry message for a certain period of time.

The MCAP support device 402 broadcasts an IGMP inquiry message for the multicast group 239.2525.255.250 (S404).

The MCAP support device 402 that broadcasts the MCAP broadcast message is
IG from any device on the EEE1394 network
The MP message is received (S406).

The MCAP support device 402 that broadcasts the MCAP broadcast message is the same I
I from any device on the EEE1394 network
It is determined whether the GMP message is transmitted through the designated channel (channel 17) (S40).
8).

On the IEEE 1394 network, the devices 404 and 406 belonging to the multicast group 239.2525.255.250 transmit an IGMP report message in response to the IGMP inquiry message.
The target address of the IGMP report is the MCAP support device that broadcasts the MCAP broadcast message, that is, the MCAP support device 402 that broadcasts the IGMP inquiry message.

Since the MCAP support device 406 already knows the channel number for the corresponding multicast address 239.2525.255.250 from the MCAP broadcast message, it transmits the IGMP report through the channel 7.

On the other hand, the MCAP non-supporting device 404 uses the MC
The IGMP report is transmitted through the broadcast channel (channel 31) so that the AP broadcast message is not recognized.

Therefore, the MCAP support device 402 is
It is possible to confirm whether or not each of the devices 404 and 406 supports MCAP by confirming the channel number on which these IGMP messages are transmitted.

If the IGMP message from any device on the same IEEE 1394 network is transmitted through the designated channel (channel 7), the MCAP supporting device 402 determines that all devices on the same IEEE 1394 network support MCAP. Yes (S410).

On the other hand, if the IGMP message from any device on the same IEEE 1394 network is not transmitted through the designated channel (channel 7), the MCAP supporting device 402 determines that the same IEEE 13
It is determined that not all devices on the 94 network support MCAP (S412).

The MCAP broadcast message includes an expiry time field. The end time field is for setting the time for maintaining the channel specified by the MCAP broadcast message. The MCAP Assistance Device maintains the designated channel for multicast during the time designated in the End Time field.

If the IGMP message from every device on the same IEEE 1394 network was not transmitted through the designated channel (channel 7), it is not necessary to maintain the channel designated by the MCAP broadcast message.

Accordingly, if the IGMP message from any device on the same IEEE 1394 network is not transmitted through the designated channel (channel 7), the same MCAP broadcast message with the end time = 0 (clear immediately) is transmitted. Broadcast to all devices on the network to release the channel designated for multicast (S414).

FIG. 6 is a flowchart showing a multicast communication method according to the present invention, and FIG. 7 is a schematic diagram showing the method shown in FIG.

The multicast communication method according to the present invention will be described in detail with reference to FIGS. 6 and 7.

First, as shown in FIG. 6, the MCAP supporting device 402 belonging to a certain multicast group is not a broadcast channel but an arbitrary channel (multicast channel, for example, channel 7).
Is assigned to a multicast address, and an MCAP broadcast message is broadcast to all devices on the same IEEE 1394 network through this multicast channel (S602).

Next, the MCAP support device 402 that broadcasts the MCAP broadcast message receives the same IEEE 139 through the broadcast channel.
4 Broadcast an IGMP inquiry message to all devices on the network (S604).

The MCAP supporting device 402 that broadcasts the MCAP broadcast message is
IG from any device on the EEE1394 network
The MP message is received (S606).

The MCAP support device 402 that has broadcast the MCAP broadcast message is the same I
I from any device on the EEE1394 network
It is determined whether the GMP message is transmitted through the designated channel (channel 7) (S60).
8).

The devices 404 and 406 that belong to the multicast group 239.2525.255.250 on the IEEE 1394 network transmit an IGMP report message in response to the IGMP inquiry message. The target address of the IGMP report is the MCAP support device that broadcasts the MCAP broadcast message, that is, the MCAP support device 402 that broadcasts the IGMP inquiry message.

Since the MCAP support device 406 already knows the channel number for the corresponding multicast address 239.2525.255.250 from the MCAP broadcast message, it transmits the IGMP report through the channel 7.

On the other hand, the MCAP non-support device 404 is
In order not to recognize AP broadcast messages,
The IGMP report is transmitted through the broadcast channel (channel 31).

Therefore, the MCAP support device 402 is
It is possible to confirm whether or not each of the devices 404 and 406 supports MCAP by confirming the channel number on which these IGMP messages are transmitted.

If an IGMP message from any device on the same IEEE 1394 network is transmitted through the designated channel (channel 7), the MCAP supporting device 402 determines that all devices on the same IEEE 1394 network support MCAP. Yes (S610). The MCAP support device 402 transmits / receives to / from the corresponding multicast address using the multicast channel (S616).

On the other hand, if the IGMP message from any device on the same IEEE 1394 network is not transmitted through the designated channel (channel 7), the MCAP supporting device 402 determines the same IEEE 13
It is determined that not all devices on the 94 network support MCAP (S612). MCAP
The supporting device 402 broadcasts an MCAP broadcast message having the content of end time = 0 (release immediately) to all devices on the same network (S614).

The MCAP support device 402 transmits / receives to / from the corresponding multicast address using the broadcast channel (S616).

As shown in FIG. 7, the MCAP supporting device 402 is assigned to transmit / receive to / from the corresponding multicast address 239.255.255.250 if any IGMP report is received through the designated channel channel 7. Channel The channel 7 is used, and if the IGMP report is received through at least one broadcast channel (channel 31), the MCAP support device 402 also broadcasts using the broadcast channel (channel 31).

That is, when all devices belonging to a certain multicast group support MCAP, multicast communication by the MCAP protocol is performed,
If there is a device that does not support MCAP, multicast communication using the broadcast method is performed.

[0083]

As described above, according to the present invention, the IEEE
Even if all devices belonging to the multicast group on the 1394 network support the MCAP, it is possible to prevent useless use of the broadcast channel to give a computational load to the devices. Even if there is a non-MCAP supporting device, multicast communication is possible.

[Brief description of drawings]

FIG. 1 is a unicast system, a broadcast system,
3 is a diagram schematically showing a multicast method.

FIG. 2 is a diagram schematically showing a relationship between layers in IEEE 1394.

3A and 3B are drawings schematically showing a conventional multicast communication system on an IEEE 1394 network.

FIG. 4 is a flowchart illustrating a method of identifying whether to support MCAP according to the present invention.

FIG. 5 is a diagram schematically showing the process shown in FIG.

FIG. 6 is a flowchart showing a multicast communication method according to the present invention.

7 is a diagram schematically showing the method shown in FIG. 6;

[Explanation of symbols]

302, 306, 402, 406 MCAP support equipment 304,404 MCAP non-supporting device

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5K033 AA01 CB13 CC01 DA11 DB14                       DB16 EC03

Claims (10)

[Claims] 1. (a) MCAP (Multicast)
Channel Allocation Protoco
1) a process in which the supporting device broadcasts an MCAP broadcast message to all devices on the same network; and (b) the MCAP supporting device that broadcasts the MCAP broadcast message sends IGMP (Internet GTP) messages to all devices on the same network.
loop Management Protocol) inquiry message is broadcasted, and (c) the MCAP supporting device that broadcasts the MCAP broadcast message causes the MCAP supporting device to transmit an IGMP report message from all devices on the same network, and the MCAP supporting device broadcasts the MCAP supporting message to each device. And a method of checking whether or not to support MCAP on the same network, including a step of identifying whether or not to support. 2. The step (c) comprises determining that all devices on the network do not support MCAP unless the IGMP report message is transmitted through a channel designated by the MCAP broadcast message. The method for confirming whether to support MCAP on the same network according to claim 1. 3. (d) The IGMP report message is M
The method further comprises the step of broadcasting an MCAP broadcast message instructing every device on the network to release the specified channel unless it is transmitted through the channel specified by the CAP broadcast message. MCA on the same network according to item 2
How to confirm whether to support P. 4. The method as claimed in claim 3, wherein the step (d) broadcasts an MCAP broadcast message specifying'end time '= 0. Method. 5. The method for confirming whether to support MCAP on the same network according to claim 1, wherein the network is an IEEE 1394 network. 6. A process of (a) an MCAP supporting device belonging to a certain multicast group broadcasting an MCAP broadcast message to all devices on the same network, and (b) an MCAP supporting device broadcasting the MCAP broadcast message, By the process of broadcasting an IGMP inquiry message to all devices on the same network, and (c) the MCAP support device that broadcasts the MCAP broadcast message uses a channel number to transmit an IGMP report message from all devices on the same network. A process of identifying whether or not each device supports MCAP, and (e) an IG from every device that broadcasts the MCAP broadcast message. If the MP report message is transmitted through the multicast channel, transmission / reception for the corresponding multicast address is performed using the multicast channel, and if even one is transmitted through the broadcast channel, transmission / reception for the corresponding multicast address is performed using the broadcast channel. And a multicast communication method on the same network including a process. 7. The step (c) determines that all devices on the network do not support MCAP unless the IGMP report message is transmitted through a channel designated by an MCAP broadcast message. 7. The multicast communication method on the same network according to claim 6. 8. (d) In the step (c), the IGMP
If the report message is not transmitted through the channel designated by the MCAP broadcast message, the method further comprises the step of broadcasting an MCAP broadcast message instructing all devices on the network to release the designated channel. The multicast communication method on the same network according to claim 7. 9. The multicast communication method on the same network according to claim 8, wherein the step (d) broadcasts an MCAP broadcast message designating'end time '= 0. 10. The network is IEEE 1394
The multicast communication method on the same network according to claim 6, which is a network.